Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:

#include<iostream>
#include<queue>
using namespace std;
typedef struct{
  int x,y;
}Point;
 
int dx[4]={0,1,0,-1};
int dy[4]={-1,0,1,0};
char mp[51][51];
int d[51][51];
#define INF 100000
int main(){
  int h,w,sx,sy,gx,gy,cnt=0;
  cin>>h>>w;
  gx=w-1;
  gy=h-1;
  sx=0;
  sy=0;
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      cin>>mp[i][j];
      d[i][j]=INF;
      if(mp[i][j]=='.'){
	cnt++;
      }

    }
  }
  queue<Point>que;
  que.push((Point){sx,sy});
  d[sy][sx]=0;
  while(!que.empty()){
    Point p=que.front();
    que.pop();
    int x=p.x;
    int y=p.y;
    if(x==gx && y==gy){
      break;
    }
    for(int i=0;i<4;i++){
      int nx=x+dx[i];
      int ny=y+dy[i];
      if(nx>=0&&nx<w&&ny>=0&&ny<h&&mp[ny][nx]!='#'&&d[ny][nx]==INF){
        d[ny][nx]=d[y][x]+1;
        que.push((Point){nx,ny});
      }
    }
  }
  if(d[gy][gx]==INF){
    cout<<-1<<endl;
  }else{
    cout<<cnt-d[gy][gx]-1<<endl;
  }
  return(0);
}